/****************************************************************************
 *
 * Copyright 2016 Samsung Electronics All Rights Reserved.
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 * http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing,
 * software distributed under the License is distributed on an
 * "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND,
 * either express or implied. See the License for the specific
 * language governing permissions and limitations under the License.
 *
 ****************************************************************************/
/****************************************************************************
 * fs/dirent/fs_rewinddir.c
 *
 *   Copyright (C) 2007-2009, 2011, 2014 Gregory Nutt. All rights reserved.
 *   Author: Gregory Nutt <gnutt@nuttx.org>
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions
 * are met:
 *
 * 1. Redistributions of source code must retain the above copyright
 *    notice, this list of conditions and the following disclaimer.
 * 2. Redistributions in binary form must reproduce the above copyright
 *    notice, this list of conditions and the following disclaimer in
 *    the documentation and/or other materials provided with the
 *    distribution.
 * 3. Neither the name NuttX nor the names of its contributors may be
 *    used to endorse or promote products derived from this software
 *    without specific prior written permission.
 *
 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
 * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
 * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS
 * FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE
 * COPYRIGHT OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT,
 * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING,
 * BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS
 * OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED
 * AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN
 * ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
 * POSSIBILITY OF SUCH DAMAGE.
 *
 ****************************************************************************/

/****************************************************************************
 * Included Files
 ****************************************************************************/

#include <tinyara/config.h>

#include <dirent.h>
#include <errno.h>

#include <tinyara/fs/fs.h>
#include <tinyara/fs/dirent.h>

#include "inode/inode.h"

/****************************************************************************
 * Private Functions
 ****************************************************************************/

/****************************************************************************
 * Name: rewindpseudodir
 ****************************************************************************/

static inline void rewindpseudodir(struct fs_dirent_s *idir)
{
	struct inode *prev;

	inode_semtake();

	/* Reset the position to the beginning */

	prev = idir->u.pseudo.fd_next;	/* (Save to delete later) */
	idir->u.pseudo.fd_next = idir->fd_root;	/* The next node to visit */
	idir->fd_position = 0;		/* Reset position */

	/* Increment the reference count on the root=next node.  We
	 * should now have two references on the inode.
	 */

	idir->fd_root->i_crefs++;
	inode_semgive();

	/* Then release the reference to the old next inode */

	if (prev) {
		inode_release(prev);
	}
}

/****************************************************************************
 * Public Functions
 ****************************************************************************/

/****************************************************************************
 * Name: rewinddir
 *
 * Description:
 *   The  rewinddir() function resets the position of the
 *   directory stream dir to the beginning of the directory.
 *
 * Inputs:
 *   dirp -- An instance of type DIR created by a previous
 *     call to opendir();
 *
 * Return:
 *   None
 *
 ****************************************************************************/

void rewinddir(FAR DIR *dirp)
{
	struct fs_dirent_s *idir = (struct fs_dirent_s *)dirp;
#ifndef CONFIG_DISABLE_MOUNTPOINT
	struct inode *inode;
#endif

	/* Verify that we were provided with a valid directory structure,
	 * A special case is when we enumerate an "empty", unused inode (fd_root
	 * == 0).  That is an inode in the pseudo-filesystem that has no
	 * operations and no children.  This is a "dangling" directory entry that
	 * has lost its children.
	 */

	if (!idir || !idir->fd_root) {
		return;
	}

	/* The way we handle the readdir depends on the type of inode
	 * that we are dealing with.
	 */

#ifndef CONFIG_DISABLE_MOUNTPOINT
	inode = idir->fd_root;
	if (INODE_IS_MOUNTPT(inode)) {
		/* The node is a file system mointpoint. Verify that the mountpoint
		 * supports the rewinddir() method
		 */

		if (inode->u.i_mops && inode->u.i_mops->rewinddir) {
			/* Perform the rewinddir() operation */

			inode->u.i_mops->rewinddir(inode, idir);
		}
	} else
#endif
	{
		/* The node is part of the root pseudo file system */

		rewindpseudodir(idir);
	}
}
